U.S. patent number 7,528,218 [Application Number 11/559,711] was granted by the patent office on 2009-05-05 for polyester for toner.
This patent grant is currently assigned to Kao Corporation. Invention is credited to Eiji Shirai, Tetsuya Ueno.
United States Patent |
7,528,218 |
Shirai , et al. |
May 5, 2009 |
Polyester for toner
Abstract
The present invention relates to a polyester for a toner,
obtained by polycondensing an alcohol component and a carboxylic
acid component containing an alkylsuccinic acid having 10 or more
carbon atoms, an alkenylsuccinic acid having 10 or more carbon
atoms, or a mixture thereof, in an amount of from 0.5 to 50% by
mole, wherein each of 6-methyl-2-heptanone and 5-methyl-2-heptanone
is detected in an amount of 0.5 ppm or less as determined by
thermal desorption-gas chromatography-mass spectrometry. The
polyester for a toner of the present invention is used as a resin
binder, or the like, for a toner used, for example, for developing
electrostatic latent images formed in electrophotography,
electrostatic recording method, electrostatic printing method, or
the like.
Inventors: |
Shirai; Eiji (Wakayama,
JP), Ueno; Tetsuya (Wakayama, JP) |
Assignee: |
Kao Corporation (Tokyo,
JP)
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Family
ID: |
38056278 |
Appl.
No.: |
11/559,711 |
Filed: |
November 14, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070135615 A1 |
Jun 14, 2007 |
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Foreign Application Priority Data
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Dec 12, 2005 [JP] |
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2005-357910 |
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Current U.S.
Class: |
528/272;
430/108.4; 430/109.2; 430/109.4; 524/445; 524/492; 524/589;
524/599; 524/99; 528/271 |
Current CPC
Class: |
C08G
63/16 (20130101); C08G 63/20 (20130101); C08G
63/52 (20130101); C08G 63/668 (20130101); C08G
63/78 (20130101); G03G 9/08755 (20130101) |
Current International
Class: |
C08G
63/02 (20060101); C08G 63/00 (20060101) |
Field of
Search: |
;430/108.4,109.2,109.4
;524/99,445,492,589,599 ;528/271,272 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1018982 |
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Feb 1966 |
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GB |
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5-27480 |
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Feb 1993 |
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JP |
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6-27728 |
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Feb 1994 |
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JP |
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8-30025 |
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Feb 1996 |
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JP |
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2000-35695 |
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Feb 2000 |
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JP |
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2000-214633 |
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Aug 2000 |
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JP |
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2002-333736 |
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Nov 2002 |
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JP |
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2005-350511 |
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Dec 2005 |
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JP |
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Primary Examiner: Boykin; Terressa M
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. A polyester toner component, obtained by polycondensing an
alcohol component and a carboxylic acid component containing an
alkylsuccinic acid having 10 or more carbon atoms, an
alkenylsuccinic acid having 10 or more carbon atoms, or a mixture
thereof, in an amount of from 0.5 to 50% by mole, wherein each of
6-methyl-2-heptanone and 5-methyl-2-heptanone is detected in an
amount of 0.5 ppm or less as determined by thermal desorption-gas
chromatography-mass spectrometry.
2. The polyester toner component according to claim 1, wherein a
ratio of a total peak area attributed to ketone compounds having 4
to 8 carbon atoms (KS) and a peak area attributed to acetone (AS),
i.e. KS/AS, is from 0.1 to 3.0, as determined by solid-phase
microextraction-gas chromatography-mass spectrometry.
3. The polyester toner component according to claim 1, wherein an
alkylsuccinic acid having 11 to 13 carbon atoms, an alkenylsuccinic
acid having 11 to 13 carbon atoms, or a mixture thereof, is
contained in an amount of 70% by mole or more, of the alkylsuccinic
acid having 10 or more carbon atoms, the alkenylsuccinic acid
having 10 or more carbon atoms, or a mixture thereof.
4. The polyester toner component according to claim 1, comprising a
trivalent or higher polyvalent monomer is contained in an amount of
from 1 to 25% by mole of a total amount of the alcohol component
and the carboxylic acid component.
5. The polyester toner component according to claim 1, wherein an
alkylene oxide adduct of bisphenol A, represented by the formula
(I): ##STR00002## wherein RO is an alkylene oxide; R is an alkylene
group having 2 or 3 carbon atoms; x and y are positive numbers
showing an average number of moles of alkylene oxide, wherein a sum
of x and y is from 1 to 16, is contained in an amount of 90% by
mole or more, of the alcohol component.
6. A process for producing a polyester toner component, comprising
the step of polycondensing an alcohol component and a carboxylic
acid component containing an alkylsuccinic acid having 10 or more
carbon atoms, an alkenylsuccinic acid having 10 or more carbon
atoms, or a mixture thereof, in an amount of from 0.5 to 50% by
mole, wherein water is added to a reaction system at a temperature
of from 100.degree. to 300.degree. C. during, after, or during and
after the reaction of an alcohol component and an alkylsuccinic
acid having 10 or more carbon atoms, an alkenylsuccinic acid having
10 or more carbon atoms, or a mixture thereof, in an amount of from
0.1 to 50 parts by weight, based on 100 parts by weight of the
polyester obtained.
7. The process according to claim 6, wherein each of
6-methyl-2-heptanone and 5-methyl-2-heptanone is detected in the
resulting polyester in an amount of 0.5 ppm or less as determined
by thermal desorption-gas chromatography-mass spectrometry.
8. The process according to claim 6, wherein water is added to the
reaction system under a pressure of from 4 to 100 kPa.
9. The process according to claim 6, wherein the polycondensation
reaction is carried out under at least two stages of reaction
temperatures, wherein said reaction temperatures are (i) a
temperature of from 225.degree. to 245.degree. C., and (ii) a
temperature lower than the temperature in (i) by 20.degree. to
60.degree. C.
10. A toner comprising the polyester for a toner as defined in
claim 1.
11. A toner comprising the polyester for a toner as defined in
claim 2.
12. A toner comprising the polyester for a toner as defined in
claim 3.
13. A toner comprising the polyester for a toner as defined in
claim 4.
14. A toner comprising the polyester for a toner as defined in
claim 5.
Description
FIELD OF THE INVENTION
The present invention relates to a polyester for a toner used, for
example, for developing electrostatic latent images formed in
electrophotography, electrostatic recording method, electrostatic
printing method or the like, a process for producing the polyester,
and a toner containing the polyester.
BACKGROUND OF THE INVENTION
A toner used for an electrophotographic system, especially, an
electrophotographic system using a heat roller fixing system, has
been desired to have excellent low-temperature fixing ability and
offset resistance. In view of the above, JP2000-35695 A discloses
that a polyester resin obtained by using an alkylsuccinic acid, an
alkenylsuccinic acid, or a mixture thereof, each having 10 or more
carbon atoms, is excellent in low-temperature fixing ability and
offset resistance.
SUMMARY OF THE INVENTION
The present invention relates to:
(1) a polyester for a toner, obtained by polycondensing an alcohol
component and a carboxylic acid component containing an
alkylsuccinic acid having 10 or more carbon atoms, an
alkenylsuccinic acid having 10 or more carbon atoms, or a mixture
thereof, in an amount of from 0.5 to 50% by mole, wherein each of
6-methyl-2-heptanone and 5-methyl-2-heptanone is detected in an
amount of 0.5 ppm or less as determined by thermal desorption-gas
chromatography-mass spectrometry; (2) a process for producing a
polyester for a toner, including the step of polycondensing an
alcohol component and a carboxylic acid component containing an
alkylsuccinic acid having 10 or more carbon atoms, an
alkenylsuccinic acid having 10 or more carbon atoms, or a mixture
thereof, in an amount of from 0.5 to 50% by mole, wherein water is
added to a reaction system at a temperature of from 100.degree. to
300.degree. C. during, after, or during and after the reaction of
an alcohol component and an alkylsuccinic acid having 10 or more
carbon atoms, an alkenylsuccinic acid having 10 or more carbon
atoms, or a mixture thereof, in an amount of from 0.1 to 50 parts
by weight, based on 100 parts by weight of the polyester obtained;
and (3) a toner containing the polyester for a toner as defined in
the above (1).
DETAILED DESCRIPTION OF THE INVENTION
A toner containing a polyester obtained by using an alkylsuccinic
acid having 10 or more carbon atoms, an alkenylsuccinic acid having
10 or more carbon atoms, or a mixture thereof, has a disadvantage
of staining in the machine in an electrophotographic system, in
particular, staining of a charging member, such as corotron or
scorotron.
The present invention relates to a polyester for a toner which is
excellent in low-temperature fixing ability and offset resistance,
and also capable of reducing staining in the machine, and a process
for producing the polyester, and a toner containing the
polyester.
The polyester for a toner of the present invention is excellent in
low-temperature fixing ability and offset resistance, and also
exhibits an excellent effect of being capable of reducing staining
in the machine.
These and other advantages of the present invention will be
apparent from the following description.
The polyester for a toner of the present invention is a polyester
for a toner obtained by polycondensing an alcohol component and a
carboxylic acid component containing an alkylsuccinic acid, an
alkenylsuccinic acid, or a mixture thereof, each having 10 or more
carbon atoms, and has a feature that 6-methyl-2-heptanone and
5-methyl-2-heptanone are detected in an amount within a certain
range as determined by thermal desorption-gas chromatography-mass
spectrometry (TD-GC/MS). The polyester obtained by using an
alkylsuccinic acid, an alkenylsuccinic acid, or a mixture thereof
as raw materials monomers is more likely to cause staining in the
machine in an electrophotographic system, while being excellent in
low-temperature fixing ability and offset resistance. In view of
the above, as a result of studies, the present inventors have found
that staining in the machine is caused by a volatilization of
impurities and the like in a toner by temperature elevation in the
machine during image printing. As a result of further studies, it
has been found that staining in the machine can be suppressed if
specified ketone components which are volatile under specified
temperature conditions, specifically, 6-methyl-2-heptanone and
5-methyl-2-heptanone, are reduced.
In the present invention, the thermal desorption-gas
chromatography-mass spectrometry (TD-GC/MS) which is used for the
detection of 6-methyl-2-heptanone, 5-methyl-2-heptanone, or a
mixture thereof detects a component, which is volatized while
heating, by way of trapping (heat-desorbing) the component,
separating the trapped component into each component by gas
chromatography, and performing mass spectrometry. In the present
invention, a sample is heated under the conditions similar to the
environment in the machine, specifically, heated at a temperature
of 120.degree. C. for 1 hour, and whereby 6-methyl-2-heptanone and
5-methyl-2-heptanone which are causative of staining in the machine
can be detected by using TD-GC/MS as a measuring means under the
above conditions.
A detected amount of 6-methyl-2-heptanone and 5-methyl-2-heptanone
is each 0.5 ppm or less, preferably 0.3 ppm or less, and more
preferably 0.1 ppm or less. A total detected amount of
6-methyl-2-heptanone and 5-methyl-2-heptanone is preferably 1.0 ppm
or less, and more preferably 0.6 ppm or less.
Further, the polyester according to the present invention has a
ratio of a total peak area attributed to ketone compounds having 4
to 8 carbon atoms (KS) and a peak area attributed to acetone (AS),
i.e. KS/AS, is preferably from 0.1 to 3.0, more preferably from 0.5
to 2.5, and even more preferably from 1.0 to 2.0, as determined by
solid-phase microextraction-gas chromatography-mass spectrometry
(SPME-GC/MS), from the viewpoint of suppression of staining in the
machine, in particular, staining of a charging member.
Solid-phase microextraction (SPME) is a method of performing gas
chromatography-mass spectrometry, including the steps of adsorbing
chemical substance in a sample to a solid phase bound to a fine
needle (referred to as fiber), inserting the needle into an inlet
of GC/MS after adsorption, and heat-desorbing the chemical
substance adsorbed to the solid phase. The generation of staining
in the machine markedly takes place in a charging member, such as
corotron or scorotron. In the present invention, the adsorption to
a solid phase according to SPME under heating conditions at a
temperature of 45.degree. C. for 30 minutes after heating a sample
at 180.degree. C. for 10 minutes in advance is regarded to
reproduce adsorption (staining) of a volatile component of a toner
to a charging member caused by temperature elevation in the
machine.
The ketone compound having 4 to 8 carbon atoms includes 2-butanone,
3-methyl-2-butanone, 3-buten-2-one, 2-pentanonediacetyl,
3-methyl-3-buten-2-one, 4-methyl-2-pentanone, 3-methyl-2-pentanone,
2-hexanone, 4-methyl-2-hexanone, 2-heptanone, 3-methyl-2-heptanone,
4-methyl-2-heptanone, 6-methyl-2-heptanone, 5-methyl-2-heptanone,
and the like.
The polyester for a toner of the present invention is obtained by
polycondensing an alcohol component and a carboxylic acid
component, using the alcohol component and a carboxylic acid
component containing an alkylsuccinic acid, an alkenylsuccinic
acid, or a mixture thereof, each having 10 or more carbon atoms, as
raw material monomers. The phrase "an alkylsuccinic acid, an
alkenylsuccinic acid, or a mixture thereof, each having 10 or more
carbon atoms" as used herein refers to a succinic acid substituted
by an alkyl group having 10 or more carbon atoms, a succinic acid
substituted by an alkenyl group having 10 or more carbon atoms, or
a mixture thereof.
The alkylsuccinic acid and the alkenylsuccinic acid, each having 10
or more carbon atoms, are effective in improving low-temperature
fixing ability and offset resistance. The alkylsuccinic acid or the
alkenylsuccinic acid is contained in an amount, or in a total
amount, when both are used together, of from 0.5 to 50% by mole,
preferably from 5 to 40% by mole, and more preferably from 8 to 30%
by mole, of the carboxylic acid component.
The alkylsuccinic acid having 10 or more carbon atoms includes
undecylsuccinic acid, dodecylsuccinic acid, tridecylsuccinic acid,
tetradecylsuccinic acid, pentadecylsuccinic acid, hexadecylsuccinic
acid, heptadecylsuccinic acid, octadecylsuccinic acid,
nonadecylsuccinic acid, and the like. Also, the alkenylsuccinic
acid having 10 or more carbon atoms includes undecenylsuccinic
acid, dodecenylsuccinic acid, tridecenylsuccinic acid,
tetradecenylsuccinic acid, pentadecenylsuccinic acid,
hexadecenylsuccinic acid, heptadecenylsuccinic acid,
octadecenylsuccinic acid, nonadecenylsuccinic acid, and the
like.
Among the alkylsuccinic acid and the alkenylsuccinic acid, each
having 10 or more carbon atoms, an alkylsuccinic acid and an
alkenylsuccinic acid, each having 11 to 13 carbon atoms, such as
undecylsuccinic acid, dodecylsuccinic acid, tridecylsuccinic acid,
undecenylsuccinic acid, dodecenylsuccinic acid, and
tridecenylsuccinic acid, are preferable from the viewpoint of the
prevention of staining in the machines. The alkylsuccinic acid or
the alkenylsuccinic acid, each having 11 to 13 carbon atoms, is
contained in an amount of preferably 70% by mole or more, more
preferably 80% by mole or more, and even more preferably 85% by
mole or more, of the alkylsuccinic acid, the alkenylsuccinic acid,
or a mixture thereof, each having 10 or more carbon atoms.
A dicarboxylic acid component other than the alkylsuccinic acid and
the alkenylsuccinic acid, each having 10 or more carbon atoms,
includes an aromatic dicarboxylic acid such as phthalic acid,
isophthalic acid, and terephthalic acid; an aliphatic dicarboxylic
acid such as oxalic acid, malonic acid, maleic acid, fumaric acid,
citraconic acid, itaconic acid, glutaconic acid, succinic acid,
adipic acid, and a succinic acid substituted by an alkyl group
having 1 to 9 carbon atoms or an alkenyl group having 2 to 9 carbon
atoms, such as octylsuccinic acid; an acid anhydride thereof and an
acid alkyl (1 to 3 carbon atoms) ester thereof, and the like. Among
them, the aromatic dicarboxylic acid compounds are preferable, from
the viewpoint of durability, fixing ability, and dispersibility of
a colorant. The carboxylic acid, the anhydride of the carboxylic
acid and the alkyl ester of the carboxylic acid are collectively
referred to herein as a carboxylic acid compound.
The aromatic dicarboxylic acid compound is contained in an amount
of preferably from 50 to 99.5% by mole, more preferably from 60 to
95% by mole, even more preferably from 60 to 92% by mole, and even
more preferably from 70 to 92% by mole, of the dicarboxylic acid
component.
A tricarboxylic or higher polycarboxylic acid component includes
1,2,4-benzenetricarboxylic acid (trimellitic acid),
2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and acid
anhydrides thereof, lower alkyl(1 to 3 carbon atoms) esters
thereof; and the like.
On the other hand, it is preferable that the alcohol component
contains an alkylene oxide adduct of bisphenol A represented by the
formula (I):
##STR00001## wherein RO is an alkylene oxide; R is an alkylene
group having 2 or 3 carbon atoms; x and y are positive numbers
showing an average number of moles of alkylene oxide added, wherein
a sum of x and y is from 1 to 16, and preferably from 1.5 to 5,
from the viewpoint of satisfying both fixing ability and
durability.
Specific examples of the alkylene oxide adduct of bisphenol A
represented by the formula (I) include
polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane,
polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, and the
like.
The above-mentioned alkylene oxide adduct of bisphenol A is
contained in an amount of preferably 90% by mole or more, more
preferably from 95 to 100% by mole, and even more preferably
substantially 100% by mole, of the alcohol component.
A dihydric alcohol other than the above-mentioned alkylene oxide
adduct of bisphenol A includes ethylene glycol, 1,2-propylene
glycol, 1,4-butanediol, neopentyl glycol, polyethylene glycol,
polypropylene glycol, hydrogenated bisphenol A, and the like.
A trihydric alcohol or higher polyhydric alcohol includes, for
example, sorbitol, pentaerythritol, glycerol, trimethylolpropane,
and the like.
It is preferable that the raw material monomer contains a trivalent
or higher polyvalent monomer. The trivalent or higher polyvalent
monomer, specifically, a trihydric alcohol or higher polyhydric
alcohol, a tricarboxylic or higher polycarboxylic acid compound, or
a mixture thereof, and preferably a tricarboxylic or higher
polycarboxylic acid compound, is contained in an amount of
preferably from 1 to 25% by mole, and more preferably from 5 to 20%
by mole, of a total amount of the alcohol component and the
carboxylic acid component, from the viewpoint of durability.
Further, the raw material monomer may properly contain a monohydric
alcohol and a monocarboxylic acid compound within the range which
would not impair the effects of the present invention, from the
viewpoint of adjusting the molecular weight or the like.
The polyester can be obtained, for example, through the step of
polycondensing an alcohol component and a carboxylic acid component
at a temperature of from 180.degree. to 250.degree. C. in an inert
gas atmosphere, optionally in the presence of an esterification
catalyst. When the polyester of the present invention is produced,
it is preferable the polycondensing step includes the step of
forming an azeotrope with water in order to remove
6-methyl-2-heptanone, 5-methyl-2-heptanone, or the like which is
causative of the source of staining in a resin.
Specifically, the process including the step of forming an
azeotrope with water in the polycondensation reaction includes a
process including the step of adding water to a reaction system at
a temperature of from 100.degree. to 300.degree. C., during, after,
or during and after the reaction of an alcohol component and an
alkylsuccinic acid, an alkenylsuccinic acid, or a mixture thereof,
each having 10 or more carbon atoms, in the process for producing a
polyester for a toner including the step of polycondensing the
alcohol component and the carboxylic acid component which contains
the alkylsuccinic acid, the alkenylsuccinic acid, or a mixture
thereof, each having 10 or more carbon atoms, in an amount of from
0.5 to 50% by mole.
The water to be added to the reaction system is in an amount of
preferably from 0.1 to 50 parts by weight, more preferably from 0.5
to 40 parts by weight, and even more preferably from 1 to 30 parts
by weight, based on 100 parts by weight of the resulting
polyester.
The temperature in the reaction system at which water is added is
preferably from 100.degree. to 300.degree. C., more preferably from
130.degree. to 250.degree. C., and even more preferably from
150.degree. to 240.degree. C., from the viewpoint of evaporation
efficiency of water and viscosity of the reaction mixture.
The method of adding water to a reaction system is not particularly
limited, and includes, for example, a method of mixing water in the
form of a liquid and a reactant; a method of contacting water in
the form of a liquid or gas (steam) with a reactant; and the like.
A method of mixing water in the form of a liquid and a reactant at
a temperature of preferably from 10.degree. to 60.degree. C., and
more preferably from 15.degree. to 50.degree. C., is desired, and a
method of blowing steam at a temperature of preferably from
100.degree. to 260.degree. C., and more preferably from 120.degree.
to 180.degree. C. into a reactant, is more desired. In a bubbling
method such as a method of blowing air or nitrogen, when viscosity
of a resin is high, each bubble becomes larger and there is no
interaction between the bubble and the resin, so that a sufficient
efficiency is not obtained. When steam is blown thereinto, it is
expected that steam is allowed to expand and diffuse because the
temperature of steam is lower than that of the reactant, and
consequently, fine bubbles are allowed to diffuse extensively and
homogeneously, or to evaporate involving a low-boiling point
substance in the resin during expansion and diffusion.
The pressure inside the reaction system when adding water is
preferably from 4 to 100 kPa, more preferably from 6 to 90 kPa, and
even more preferably from 20 to 60 kPa, from the viewpoint of
efficient diffusion of water.
The rate of adding water to the reaction system is preferably from
0.002 to 0.5 parts by weight/min, more preferably from 0.008 to 0.3
parts by weight/min, and even more preferably from 0.008 to 0.2
parts by weight/min, based on 100 parts by weight of the resulting
polyester.
Staining in the machines which is an objective of the present
invention is presumably caused by impurities contained in the
alkylsuccinic acid, the alkenylsuccinic acid, or a mixture thereof
or a decomposed product thereof formed by pyrolysis of a part of
the alkylsuccinic acid, the alkenylsuccinic acid, or a mixture
thereof during a reaction of the polyester, and especially, the
latter is regarded as the main cause because staining in the
machines takes place markedly when the reaction temperature is
high. Therefore, it is preferable that the step of adding water to
the reaction system is carried out at a point or after the
temperature reaches to the highest point in the entire
polycondensation reaction, and it is more preferable that the step
of adding water is carried out at a temperature lower than the
highest temperature after passing the highest temperature of the
entire polycondensation reaction, from the viewpoint of the
suppression of pyrolysis.
Therefore, it is preferable that the polycondensation reaction of
the polyester of the present invention is carried out in at least
two stages of reaction temperatures, and it is more preferable that
the polycondensation reaction is carried out at a reaction
temperature lower than the highest temperature by at least one
stage after the polycondensation reaction at the highest reaction
temperature. The highest reaction temperature is preferably from
225.degree. to 245.degree. C. and more preferably from 230.degree.
to 240.degree. C. On the other hand, the lower reaction temperature
is preferably from 180.degree. to 215.degree. C. and more
preferably from 200.degree. to 210.degree. C. Also, the difference
between the highest reaction temperature and a reaction temperature
after the highest reaction temperature is preferably from
20.degree. to 60.degree. C. and more preferably from 25.degree. to
45.degree. C., from the viewpoint of preventing an increase in
staining substances due to pyrolysis.
The more preferred process for producing the polyester of the
present invention includes a process including the steps of
polycondensing an alkylsuccinic acid, an alkenylsuccinic acid, or a
mixture thereof, each having 10 or more carbon atoms, at the
highest reaction temperature as mentioned above, contacting,
mixing, or contacting and mixing the reactant with water, and
polycondensing a trivalent or higher polyvalent monomer, such as
trimellitic acid having a comparably high reactivity, at a low
reaction temperature as defined above. According to the process, a
polyester in which impurities such as a ketone compound are reduced
can be efficiently obtained while keeping a toll of the reaction
time to its minimum.
The polyester for a toner of the present invention has a softening
point of preferably from 70.degree. to 170.degree. C., more
preferably from 80.degree. to 160.degree. C., and even more
preferably from 90.degree. to 155.degree. C., from the viewpoint of
low-temperature fixing ability, fixable region, and storage
property of a toner. Also, the polyester has a glass transition
temperature of preferably from 40.degree. to 80.degree. C., and
more preferably from 50.degree. to 65.degree. C., from the
viewpoint of low-temperature fixing ability and storage property of
the resulting toner. The polyester has an acid value of preferably
from 1 to 40 mgKOH/g, and more preferably from 2 to 30 mgKOH/g,
from the viewpoint of chargeability and environmental stability of
the resulting toner.
By using the polyester for a toner obtained by the present
invention as a resin binder and mixing the polyester with a
colorant or the like, a toner for electrophotography which is
excellent in low-temperature fixing ability and offset resistance,
and has reduced staining in the machine, is obtained. The polyester
of the present invention is contained in an amount of preferably
from 30 to 100% by weight, more preferably from 40 to 90% by
weight, and even more preferably from 45 to 80% by weight, of the
resin binder.
As the colorants, all of the dyes and pigments which are used as
colorants for a toner can be used. The colorant includes carbon
blacks, Phthalocyanine Blue, Permanent Brown FG, Brilliant Fast
Scarlet, Pigment Green B, Rhodamine-B Base, Solvent Red 49, Solvent
Red 146, Solvent Blue 35, quinacridone, Carmine 6B, Disazoyellow,
and the like. The toner of the present invention can be either
black toners or color toners. The colorant is contained in an
amount of preferably from 1 to 40 parts by weight, and more
preferably from 2 to 10 parts by weight, based on 100 parts by
weight of the resin binder.
Raw materials in the toner other than the resin binder and the
colorant include additives such as releasing agents, charge control
agents, electric conductivity modifiers, extenders, reinforcing
fillers such as fibrous substances, antioxidants, anti-aging
agents, fluidity improvers, cleanability improvers, and the
like.
The releasing agent includes an aliphatic hydrocarbon wax such as a
low-molecular weight polypropylene, a low-molecular weight
polyethylene, a low-molecular weight polypropylene-polyethylene
copolymer, microcrystalline wax, paraffin wax, and Fischer-Tropsch
wax, and oxides thereof; an ester wax such as carnauba wax, montan
wax, and Sazole wax, and deoxidized waxes thereof; fatty acid
amides; fatty acids; higher alcohols; metal salts of fatty acids;
and the like. Among them, the aliphatic hydrocarbon wax is
preferable, and the polypropylene wax is more preferable, from the
viewpoint of releasing property and stability. The releasing agent
is contained in an amount of preferably from 0.5 to 7.0 parts by
weight, and more preferably from 1.0 to 4.0 parts by weight, based
on 100 parts by weight of the resin binder.
The process for producing a toner may be any of conventionally
known methods such as a kneading-pulverization method and an
emulsion phase-inversion method. A pulverized toner is produced by,
for example, mixing a resin binder, a colorant, an additive such as
a releasing agent, and the like, homogenously with a mixer such as
Henschel mixer, melt-kneading with a closed type kneader, a
single-screw or twin-screw extruder, an open-roller type kneader or
the like, cooling, pulverizing, and classifying the product.
Further, fine inorganic particles such as hydrophobic silica, or
fine resin particles may be added externally to the surface of the
obtained toner. The toner has a volume-median particle size
(D.sub.50) of preferably from 3 to 15 .mu.m. In the present
invention, a volume-median particle size (D.sub.50) refers to a
particle size of which cumulative volume frequency is calculated on
a volume percentage as 50% counted from the smaller particle
sizes.
The toner containing the polyester of the present invention can be
used alone as a developer in a monocomponent toner for development,
or as a developer prepared by mixing the toner and a carrier in a
two-component toner for development.
EXAMPLES
The following examples further describe and demonstrate embodiments
of the present invention. The examples are given solely for the
purposes of illustration and are not to be construed as limitations
of the present invention.
[Softening Point]
The softening point refers to a temperature at which half the
amount of the sample flows out when plotting a downward movement of
a plunger against temperature, as measured by using a flow tester
(CAPILLARY RHEOMETER "CF-500D," commercially available from
Shimadzu Corporation), in which a 1 g sample is extruded through a
nozzle having a diameter of 1 mm and a length of 1 mm while heating
the sample so as to raise the temperature at a rate of 6.degree.
C./min and applying a load of 1.96 MPa thereto with the
plunger.
[Glass Transition Temperature]
The glass transition temperature refers to a temperature of an
intersection of the extension of the baseline of equal to or lower
than the temperature of the endothermic highest peak and the
tangential line showing the maximum inclination between the
kick-off of the peak and the top of the peak, which is determined
using a differential scanning calorimeter ("DSC 210," commercially
available from Seiko Instruments, Inc.), by raising its temperature
to 200.degree. C., cooling the sample from this temperature to
0.degree. C. at a cooling rate of 10.degree. C./min, and thereafter
raising the temperature of the sample at a heating rate of
10.degree. C./min.
[Volume-Median Particle Size (D.sub.50) of Toner]
Measuring Apparatus Coulter Multisizer II (commercially available
from Beckman Coulter K.K.)
Aperture Diameter: 100 .mu.m
Analyzing Software: Coulter Multisizer AccuComp Ver. 1.19
(commercially available from Beckman Coulter K.K.)
Electrolytic solution: "Isotone II" (commercially available from
Beckman Coulter K.K.)
Dispersion: "EMULGEN 109P" (commercially available from Kao
Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved
in the above electrolytic solution so as to have a concentration of
5% by weight, to provide a dispersion. Dispersion Conditions Ten
milligrams of a test sample is added to 5 mL of the above
dispersion, and the resulting mixture is dispersed in an ultrasonic
disperser for 1 minute. Thereafter, 25 mL of the electrolytic
solution is added to the dispersion, and the resulting mixture is
dispersed in the ultrasonic disperser for another 1 minute, to
provide a sample dispersion. Measurement Conditions The above
sample dispersion is adjusted so as to have a concentration at
which the particle sizes of 30,000 particles can be determined in
20 seconds by adding 100 mL of the above electrolytic solution to
the above sample dispersion. The particle sizes of 30,000 particles
can be determined to obtain a volume-median particle size
(D.sub.50) from the particle size distribution.
Production Example 1 for RESIN
A 5 liter-four-neck flask equipped with a nitrogen inlet tube, a
dehydration tube, a stirrer, and a thermocouple was charged with
the raw material monomers shown in Table 1 other than trimellitic
anhydride, and 4 g of tin octylate. The ingredients in the flask
were reacted at 235.degree. C. for 8 hours, and further reacted at
8.3 kPa at 235.degree. C. for 1 hour. Thereafter, the temperature
of the reaction mixture was lowered to 210.degree. C., and the
pressure was then changed back to normal pressure. Thereafter,
trimellitic anhydride was added thereto, and the mixture was
reacted until a desired softening point was reached, to provide
resins A, F, and G.
Production Example 2 for Resin
The same procedures as in Production Example 1 for Resin were
carried out except that after the ingredients in the flask were
reacted at 8.3 kPa for 1 hour, the pressure was changed back to
normal pressure, 300 mL of water at 40.degree. C. was added
dropwise to the reaction mixture at 235.degree. C. over 1 hour
while stirring, and the temperature of the mixture was lowered to
210.degree. C. after dropwise addition, and trimellitic anhydride
was then added thereto, to provide a resin B.
Production Example 3 for Resin
The same procedures as in Production Example 1 for Resin were
carried out except that after the temperature of the reaction
mixture was lowered to 210.degree. C., 300 mL of water at
40.degree. C. was added dropwise to the reaction mixture over 1
hour while stirring at 40 kPa, and the pressure was changed back to
normal pressure after dropwise addition, and trimellitic anhydride
was then added thereto, to provide a resin C.
Production Example 4 for Resin
The same procedures as in Production Example 1 for Resin were
carried out except that after the temperature of the reaction
mixture was lowered to 210.degree. C., steam at 140.degree. C. was
blown into resin at a rate of 300 g/hr over 1 hour while stirring
the reaction mixture at 20 kPa, and the pressure was changed back
to normal pressure after blowing, and trimellitic anhydride was
then added thereto, to provide a resin D.
Production Example 5 for Resin
The same procedures as in Production Example 1 for Resin were
carried out except that after the ingredients in the flask were
reacted at 8.3 kPa for 1 hour, 300 mL of water at 40.degree. C. was
added dropwise to the reaction mixture at 235.degree. C. over 1
hour while stirring, and trimellitic anhydride was then added
thereto at 235.degree. C. after dropwise addition, to provide a
resin E.
Resin A to E were subjected to thermal desorption-gas
chromatography-mass spectrometry (TD-GC/MS) and solid-phase
microextraction-gas chromatography-mass spectrometry (SPME-GC/MS)
under the following measurement conditions to measure the contents
of 6-methyl-2-heptanone and 5-methyl-2-heptanone according to
TD-GC/MS, and a ratio of a total peak area attributed to ketone
compounds having 4 to 8 carbon atoms (KS) and a peak area
attributed to acetone (AS), i.e. KS/AS, according to SPME-GC/MS,
respectively.
TD-GC/MS measurement is performed by injecting 5 .mu.L of a 5 mg/L
deuterated toluene/methanol solution standard into tube packed with
Tenax TA, and weighing 10 mg of a sample.
<Measurement Conditions for TD>
Apparatus: Turbo Matrix ATD (Automatic thermal desorption (ATD)
apparatus) commercially available from Perkin Elmer
Analysis mode: 2-step desorption
Injection: twice
Conditions of thermal desorption from a tube: at 120.degree. C. for
1 hour
Conditions of adsorption to a trap tube: at -30.degree. C. for 50
minutes
Conditions of desorption from a trap tube: starting from
-30.degree. C. and heating at a rate of 40.degree. C./min up to
300.degree. C.
Purge time: 1 minute
Valve temperature: 300.degree. C.
Transfer temperature: 300.degree. C.
Column pressure: 150 kPa
Inlet split: 50 mL/min
Outlet split: 5 mL/min
Desorption: 50 mL/min
<Measurement Conditions for GC/MS>
GC apparatus: 6890N commercially available from Agilent
Technologies
MS apparatus: 5973N commercially available from Agilent
Technologies
Oven: Keeping at a temperature of 40.degree. C. for 3 minutes,
heating at a rate of 2.degree. C./min up to 70.degree. C., heating
at a rate of 5.degree. C./min up to 150.degree. C., and heating at
a rate of 10.degree. C./min up to 300.degree. C.
Column: HP5-MS (60 m.times.250 .mu.m.times.0.25 .mu.m)
Constant pressure: 150 kPa (control from ATD) MS: scan range m/z=40
to 460 Initial Area Reject: 0 Initial Peak Width: 0.097 Shoulder
Detection: off Initial Threshold: 12.0
The quantification is performed by a single-point calibration of 5
mg/L deuterated toluene/methanol solution.
[Measurement Conditions for SPME-GC/MS]
One gram of a sample is packed in a vial, and tightly sealed
therein, the sample is heated in an oven at 180.degree. C. for 10
minutes, and thereafter the heated sample is subjected to
SPME-GC/MS.
SPME: Used fiber: Carboxen/PDMS
Adsorption condition: 45.degree. C., 30 min. GC: Column: DB-WAX 60
m.times.0.25 mm Film: 0.25 .mu.m <SPME>
Manufacturer: SUPELCO
Used fiber: Carboxen.TM.-PDMS 75 .mu.m
Model number: 57319
<GC>
Manufacturer: Agilent Technologies
Model number: HP6890 series GC System
<MS>
Manufacturer: Agilent Technologies
Model number: 5973 Mass Selective Detector
TABLE-US-00001 TABLE 1 Resin A Resin B Resin C Resin D Resin E
Resin F Resin G BPA-PO .sup.1) 1225 g (70) 1225 g (70) 1225 g (70)
1225 g (70) 525 g (30) 1663 g (95) 875 g (50) BPA-EO .sup.2) 488 g
(30) 488 g (30) 488 g (30) 488 g (30) 1138 g (70) 81 g (5) 813 g
(50) Tereplithalic Acid 374 g (45) 374 g (45) 374 g (45) 374 g (45)
415 g (50) 664 g (80) 540 g (65) Dodecenylsuccinic Anhydride
.sup.3) 402 g (30) 402 g (30) 402 g (30) 402 g (30) 335 g (25) --
-- Trimellitic Anhydride 240 g (25) 240 g (25) 240 g (25) 240 g
(25) 240 g (25) 48 g (5) 288 g (30) Softening Point (.degree. C.)
150.5 148.3 149.6 151.7 103.4 98.9 151.6 Glass Transition Temp.
(.degree. C.) 60.6 59.8 60.2 61.3 59.5 60.2 67.3 Amount of
5-Methyl-2- Below Below heptanone Detected (ppm) 0.6 0.2 detection
limit detection limit 0.2 -- -- (0.10 ppm) (0.10 ppm) Amount of
6-Methyl-2- Below Below heptanone Detected (ppm) 1.5 0.2 detection
limit detection limit 0.4 -- -- (0.10 ppm) (0.10 ppm) KS/AS 5.2 2.2
1.5 1.2 2.7 -- -- Note) The amount in parenthesis is expressed as
molar ratio when the total amount of the alcohol component is
defined as 100 mole. 1)
Polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane 2)
Polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane 3)
Compositions of Dodecenylsuccinic Anhydride Numbers of Carbon Atoms
of Substituent of Succinic Acid C9 C10 C11 C12 C13 C14 C15
Compositional ratio (% by mole) 5 8 13 73 1 Below Undetected
detection limit
Examples 1 to 4 and Comparative Examples 1 and 2
One-hundred parts by weight of a resin binder as shown in Table 2,
4 parts by weight of a colorant "MONARCH 880" (commercially
available from Cabot Corporation), 0.5 parts by weight of a
negative charge control agent "BONTRON E-84" (commercially
available from Orient Chemical Co., Ltd.), and 2 parts by weight of
a polypropylene wax "NP-055" (commercially available from MITSUI
CHEMICALS, INC.) were sufficiently mixed with a Henschel mixer.
Thereafter, the mixture was melt-kneaded using a co-rotating
twin-screw extruder having an entire length of the kneading portion
of 1560 mm, a screw diameter of 42 mm and a barrel inner diameter
of 43 mm. The rotational speed of the roller was 200 r/min, the
heating temperature within the roller was 120.degree. C., the
feeding rate of the mixture was 10 kg/h, and the average residence
time was about 18 seconds. The resulting melt-kneaded product was
rolled and cooled with a cooling roller, and thereafter finely
pulverized with a jet mill, to provide a powder having a
volume-median particle size (D.sub.50) of 7.5 .mu.m.
The amount 1.0 part by weight of "Aerosil R-972" (commercially
available from Nippon Aerosil Co., LTD.) was added as an external
additive to 100 parts by weight of the resulting powder, and the
mixture was mixed with a Henschel mixer, to provide a toner.
Test Example 1
Low-Temperature Fixing Ability and Offset Resistance
A toner was loaded in a copy machine "AR-505" (commercially
available from Sharp Corporation), and an unfixed image (2
cm.times.12 cm) with an amount of toner adhesion of 0.5 mg/cm.sup.2
was obtained. The unfixed image obtained was subjected to a fixing
test by fixing with a fixing device (fixing speed: 100 mm/sec) in a
copy machine "AR-505" (commercially available from Sharp
Corporation) which was modified to enable fixing of the unfixed
image off-line, while sequentially raising the fixing temperature
from 90.degree. to 240.degree. C. in increments of 5.degree. C.
A sand-rubber eraser, of which bottom had a size of 15 mm.times.7.5
mm, to which a load of 500 g was applied was moved backward and
forward five times over a fixed image obtained at each fixing
temperature. Thereafter, the optical reflective densities of the
fixed images before and after rubbing were measured with a
reflective densitometer "RD-915" (commercially available from
Macbeth Process Measurements Co.). The temperature of the fixing
roller at which the ratio of the both optical reflective densities
(after rubbing/before rubbing) initially exceeds 70% was defined as
the lowest fixing temperature. The low-temperature fixing ability
was evaluated in accordance with the following evaluation criteria.
Also, the generation of the offset at each fixing temperature was
visually observed, and the offset resistance was evaluated
according to the following evaluation criteria. The sheets used for
fixing were "CopyBond SF-70NA" (commercially available from Sharp
Corporation, 75 g/m.sup.2). The results are shown in Table 2.
[Evaluation Criteria of Low-Temperature Fixing Ability]
.circleincircle.: Lowest fixing temperature being lower than
170.degree. C.;
.smallcircle.: Lowest fixing temperature being 170.degree. C. or
higher and lower than 190.degree. C.; and
x: Lowest fixing temperature being 190.degree. C. or higher.
[Evaluation Criteria of Offset Resistance]
.smallcircle.: Non-offset range being 80.degree. C. or higher;
and
x: Non-offset range being lower than 80.degree. C.
Test Example 2
Staining in the Machine
A toner was loaded in a copy machine "AR-505" (commercially
available from Sharp Corporation). Fixed images having a blackened
ratio of 5% were continuously printed for 5,000 sheets, and
thereafter fixed solid images having sizes of 10 cm.times.15 cm
were printed. The quality of the fixed solid images and the
staining of a charging member were visually observed, and the
staining in the machine was evaluated in accordance with the
following evaluation criteria. The sheets used for printing fixed
images having a blackened ratio of 5% were recycled paper sheets
(45 g/m.sup.2), and those for printing fixed solid images were
"CopyBond SF-70NA" (commercially available from Sharp Corporation,
75 g/m.sup.2), respectively. The results are shown in Table 2.
[Evaluation Criteria of Staining in the Machine]
.circleincircle.: Uniform solid image is obtained and no staining
of a charging member is observed; .smallcircle.: Some staining of a
charging member is observed, but uniform solid image is obtained;
and x: Staining of a charging member is observed, and some
unevenness is generated on the solid image.
TABLE-US-00002 TABLE 2 Low- Offset Staining Temperature Resis- in
the Resin Binder Fixing Ability tance Machine Ex. 1 Resin D/Resin F
= 70/30 .largecircle. .largecircle. .circleincircle. Ex. 2 Resin
C/Resin F = 80/20 .largecircle. .largecircle. .circleincircle. Ex.
3 Resin D/Resin E = 70/30 .circleincircle. .largecircle.
.largecircle. Ex. 4 Resin B/Resin E = 90/10 .circleincircle.
.largecircle. .largecircle. Comp. Resin A/Resin F = 80/20
.largecircle. .largecircle. X Ex. 1 Comp. Resin G/Resin F = 80/20 X
X .circleincircle. Ex. 2
It can be seen from the above results that the toners of Examples
are excellent in low-temperature fixing ability and offset
resistance, and also have reduced staining in the machine even
though an alkylsuccinic acid having 10 or more carbon atoms, an
alkenylsuccinic acid having 10 or more carbon atoms, or a mixture
thereof is used. On the other hand, the toner of Comparative
Example 1 containing a polyester of which amounts of
6-methyl-2-heptanone and 5-methyl-2-heptanone detected are not
reduced generates staining in the machine, and the toner of
Comparative Example 2 containing a polyester produced without using
an alkylsuccinic acid and an alkenylsuccinic acid is
disadvantageous in low-temperature fixing ability and offset
resistance even though staining in the machine is not
generated.
The polyester for a toner of the present invention is used as a
resin binder or the like, for a toner used, for example, for
developing electrostatic latent images formed in electrophotography
electrostatic recording method, electrostatic printing method, or
the like.
The present invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *